Salesforce Visualforce Page

Salesforce

How to check whether a list is empty or not in Visualforce page in Salesforce?

Sample Code:         <apex:outputPanel style="visibility:{! IF(ISNULL(PGList), 'hidden', 'visible') }">            <apex:outputText styleClass="bld" value="Public Group(s) :"/><br/>            <apex:pageBlockTable value="{!PGList}" var="PG">                <apex:column value="{!PG.Name}"/>            </apex:pageBlockTable>          </apex:outputPanel> here PGList is a list variable.